MiniMum is the latest bike idea from designer Omer Sagiv, whose previous concept bikes I featured in a 2010 post. The MiniMum was designed as a simplified city bike; as Omer says, “using the minimum production effort, and on the other hand getting maximum user experience.” The frame is made from aluminum tubes and a steel cable and features monoblades front and rear. He explains that the wire cable “supports the seatpost by maintaining a flexible tension towards the front of the bike, in a very elegant and light way- giving it also its uniqueness.” See further descriptions of Omer’s concept on the presentation boards you see here.

Interesting concept, but the first issue that I jumped out at me when I viewed the renderings was the height of the cable that serves as the effective top tube. In relationship to seat/stem height, it looks like it would require a very high step over which is not desirable if you are riding in street clothes (not to mention that fact that a high steel cable can be a bit intimidating to straddle). Short of a quick ride on a Slingshot frame many years ago though, I have no experience with tensioned cable frame designs, so I would love to hear feedback from those of you with firsthand experience. I am sure that Omer would appreciate any constructive comments on the design as well.

18 Comments

That gearing with such a small wheel looks like it could maybe get you up to 10mph. Faster than walking, but not fast enough if you’re going to mix it up with traffic. Also, the front “suspension” (I’m assuming the coil indicates this??) must work in a way with which I’m unfamiliar, as there’s no room above the wheel if the fork compresses.

Agree with Stu and Matt; the cable top tube and ridiculous suspension indicate such a total lack of thought and/or knowledge put into the design that the rest isn’t even really worth considering. Also, I remain skeptical that the single rear stay design is possible without some expensive, proprietary, and heavy hub, though this one certainly ups the ante by imagining that you could also get a coaster brake in there.

Note that on the Strida, the monoblade is on the drive side. Having a single stay on the non-drive side is a somewhat puzzling design choice as it adds a considerable amount of torque to the root of the axle for absolutely no functional benefit.

Also, the cable is not completely ridiculous. It will keep the front end of the frame from flying too far when the down tube breaks.

Right, should have specified I meant with it on the non-drive side. A small wheel like on this design and the strida helps a lot with the pedal and heel clearance issues for a mono stay, but then you end up with the gear ratio problem. With a 32cm wheel and a 3:1 gear ratio (my guesstimate from the rendering) this thing goes a whopping 10mph pedaling at 90 rpm. At that speed and level of effort a longboard would be more effective human-powered urban transportation.

What really annoys me about these continuing attempts at a mono stay rear is that they try to replace a truly simple design based on sound engineering with an affected notion of simplicity in the form of a big dumb cantilever. I say this in almost every post on here, but it remains true: people like this guy who want to design things where aesthetics take precedence over engineering should design clothing or housewares. There are many more jobs, and they will be more likely to have successful, satisfying careers if their design goals align with the clients’. No bike company wants to hire a designer whose designs look pretty but are wildly impractical.

On the Strida, the drive is on the same side as the monoblade. This means that it’s possible to remove and replace tyres and tubes without removing the wheel, which speeds up puncture repairs and reduces the number of tools you have to carry. This is probably the only advantage of a monoblade. Negating this advantage by putting the drive on the wrong side betrays a lack of thought or understanding, unless there’s some other killer advantage I’m too dumb to see. It just looks like a fashion thing.

The spectre of fashion-led design decisions also make me look again at the overall geometry of the thing. Right angles? The original Strida was dreadful to ride. It felt unstable up hill, down dale, straight and level, at any speed (I just know, okay?). Plus, it looks like a folder, with all the compromises of a folder, but doesn’t fold. If it’s not meant to fold, why not a proper frame? And nice big wheels? Also, is there an actual front brake?

Dear all, thank you all for your comments. I would like to tell you that I have built a model of the Minimum and it works. Indeed it had a few issues like you mentioned, but then I have ridden it for a month to work and am still alive. As I mentioned before design concepts in my eyes should push boundaries and stimulate other designers and manufacturers. I now disassembled the Minimum and using the mechanisms for another concept. All in all there’s no need to be bitter or angry with me, since it is just a cute little stupid bike…take it easy and take care. Omer

Omer, I am always interested in seeing your design renderings on various forums, but I can’t help thinking that if I’d actually built the bike shown above, and overcome all the structural issues highlighted, I’d have at least shown a picture of the completed bike.

It only takes a few hours to knock-up a 3d rendering but engineering and building a working bicycle prototype surely takes months or years (I know this because I am attempting to build one myself) and I do not understand why you would go to all the trouble of building and testing the bike only to release these basic renderings.

It would be great to see some photographs, then people would be able to take your statement ‘I have built it and it works’ seriously.

Omer…
The bike world would be boring and predictable without visionary designers like you. Many of the comments reflect a lack of visionary thinking from people. Looking forward to see more designs from you in the future

Omer, please show us some photos of the prototype that you have been riding and explain to us how the top wire cable is actually in tension rather than compression because for me just as all the others who commented above it appears that when the rider is on the bike that cable brings no structural benefit for the frame.

I’ll add another critic concerning the wheels: If portability comes before aspect and fashion, there should be less spokes to reduce weight. That many spokes are structurally unnecessary and add considerable weight. This choice doesn’t quite match with your “minimum” concept.

Notes on the prototype:
— Right side drive, of course
— Mag wheels (seems a little dangerous with a hub brake but at low speeds it’s probably fine)
— Gear ratio looks a little more manageable
— No front suspension
— Small but functional fenders
— Seat mast attaches to the frame outboard of the chainring. I don’t even want to know how that works.
— The cable would seem to come in and out of tension as you steer the bike because of the fork/”stem”/handlebar geometry. It would still serve the purpose of retaining broken parts, as Art points out above.
— The seat mast angle is less steep than in the renderings (STA might be as low as 60*), which puts the crank very far forward. Toe clearance is obviously pretty horrible, though that’s a problem with the strida as well and people buy it. I’m a little concerned about weight distribution, this thing looks like it would endo pretty easily.
— I think the belt is tensioned by loosening the bolts that hold the crank/seat mast assembly to the frame and moving it up the frame. Good thing it’s right side drive or fixing a flat would require taking apart the whole bike.

Ah, that’s interesting. The prototype is clearly made out of an old Strida: wheels, mudguard, frame, clamped-on bottom bracket etc. In fact, it’s a cut-down Strida with a seatpost that, weirdly, is mounted OUTSIDE the chainring. How does that work?

If the wire is there to support the seatpost, surely it would be better attached at the head tube rather than way up near the handle bars. Otherwise when under tension it’s just going to flex the bars. This move would also help with the step-over stand-over issues.